Side Effects
by rockmysocks456
Summary: The mark of Cain has left Dean feverish, delusional, and full of uncontrollable rage, Sam must deal with his sick, homicidal, older brother.
1. Chapter 1

******_* Please note I'm writing this before "Blade Runners" airs so more than likely this is not what's going to happen, but I was in the mood for some sick!Dean and Cain!Dean so... Here you are. Spoilers from season 9. No slash. Enjoy._**

* * *

The harsh, metallic tick of the clock hanging over the doorframe seemed to be amplified through the bunker. Loud, violent ticks, keeping perfect time with the deep thudding Dean knew to be his own heartbeat. Every noise around him seemed to be boring holes in his aching head. He felt hot and feverish but he was too wired to sleep. The entire sensation was vaguely reminiscent of the torturous transformation he'd undergone and the unbearable thirst that followed when he'd been turned by that mop headed vampire. However, he hadn't ingested any vampire blood recently so _what was that fucking sound?! _

He knew, somewhere deep in his imploding head, that the source of the fire that was causing his whole system to overheat was the brand that now tainted his forearm. He pulled off his flannel, threw it aside and took a ginger poke at the mark which burned as hot as it had when he'd gotten it. He tried to ignore it, ignore the pain, ignore the rage building inside him, and just work. Just focus on finding a case.

Cases were all he really had these days. With Sam firmly distancing himself, Crowley M.I.A., and Cas in the wind fighting angels, all Dean could do was continue to find cases in an attempt to get his brother back.

His vision went red, dark, blood red. He was literally seeing red. He blinked and normal color had returned except that the bunker was flooded with blood. The entire room looked like the aftermath of the elevator scene from The Shining. His heartbeat was no longer in time with the clock that was still banging each second into the manic, melting mind of the older Winchester. He looked down at the table and saw his laptop and whiskey bottle had been replaced with six or seven mutilated bodies, strewn up and down the dark wood tabletop.

He gave a startled, gravelly kind of yell and jumped up, staggering over the leg of one of the chairs, he stumbled away. He had to get away. Away from the bodies they were so... enticing. His entire sense of self was being peeled away and replaced by the very thing he hunted. Hated. But he'd always known this part of himself, just ignored it, hated it the way he hated those things he knew he could be just like. He felt such an extreme desire to kill, to mutilate bodies like those he'd just seen, though when he looked back they were gone.

He managed to get as far as the bathroom mirror where he got a good look at himself for the first time in awhile. He was pale except for the spots on his cheeks and forehead where he was deeply flushed by the fever. The dark shadows beneath his eyes only accented the clear, visible glint of red lining his green eyes. The neck of his t-shirt was soaked in sweat.

After a failed attempt to regain control by the standard splashing water in your face technique, Dean exited the bathroom. He immediately regretted it. He was hallucinating again, badly. Blood everywhere and the more he saw, the stronger the urge to slaughter became. He heard laughter. An insane, manic kind of laugh that started off softly, and slowly got louder and louder.

"Dean?!"

That was Sam's voice. What Sam could possibly have wanted or what could have woken him at 3 A.M. was a mystery to Dean. That is, until he realized the laughter was real and it was his own.

But he couldn't stop, he closed his eyes and saw dozens of methods of murder, some of him killing Sam and some of him killing strangers, ruthless and skilled.

Sam approached with caution, the psychotic laughter had naturally put him a bit on edge. Especially considering it was still happening. Though it was slowly dying out and Dean stood there, coated in sweat, eyes settling under his lids he opened them again.

Sam took a few steps closer and reached out, setting a nervous hand on Dean's shoulder. Dean practically jumped out of his skin at the slight touch, stumbling back. His eyes darted around wildly, that red glint shining against the light. The nervous energy that seemed to be racing through his system was being laced with a venomous rage he couldn't control.

"What the fuck are we doing here, Sam?!" Dean said suddenly.

Sam was startled and took a moment to respond, "What are you talking about?"

"We should be out tracking Gadreel, stabbing an angel blade through his fucking heart!" Dean barked, his voice was harsh and short, "I gotta find Abaddon and the First Blade and drag it down her meat suit and filet the bitch, hack off her limbs and then carve open her throat!"

That creepy smile was twitching at Dean's lip and another peel of laughter ring in Sam's ears as he stood, frightened of the monster he'd slowly been watching his brother become.

Dean fell silent and then grabbed his arm, the mark burning. His eyes suddenly shot closed like a sudden pain had pierced his head. His knees buckled and Sam ran forward to catch him.

He let Dean sag to the ground in his arms and then shook him gruffly,

"Dean?!"

Dean didn't respond and Sam set him down on the floor to examine him. He laid a hand across Dean's forehead and then pulled back, sensing the heat.

* * *

Dean woke feeling dazed from the fever but at least the anger was gone for now. He felt the pleasant cool of an ice pack on his head and in that same moment he became aware of the whipping of fan blades and felt the cold air blowing over him.

He opened his eyes and found the lights had been dimmed but it wasn't complete darkness which he'd likely be lost in. His blurred vision cleared up as he came to and he saw Sam sitting in a chair a few feet away, paging through a book. He looked up and saw Dean blinking, trying to sit up and he pulled his chair up closer, surveying his brother again.

"How're you feeling?" Sam asked worriedly.

"Aside from the hellfire burning in my head, just peachy." Dean groaned, sitting up and pressing the half melted ice pack to his cheek.

He shifted on his bed, sitting up most of the way so to be level with Sam. He set down the ice pack and asked, his voice scratchy and tired, "How long've I been out?"

"About fourteen hours- Hey, hey." Sam pressed a heavy hand down on Dean's shoulder as he saw him panicking, starting to get up, "It's fine, we don't have anything going on right now, it's fine."

Dean shook his head, pressing a palm into his burning temple, "Goddamn, all day...?" He trailed off, searching for words but Sam cut in.

"Dude, you do know you're _supposed _to sleep more than four hours? Anyway, you should go back to bed, you've been running a fever of 103 for the past five hours, it only just dropped to 102 before you woke up."

"How do you know my temperature?" Dean said suddenly and Sam rolled his eyes, "Oh, god, you're sticking shit in my mouth when I'm sleeping now?"

Sam gave a hollow laugh, "Not your mouth."

Dean gave a start, looking thoroughly violated.

"I used the ear thermometer, you know, for like babies because I knew you'd freak out." Sam explained, smiling.

Dean nodded and then turned to look at Sam, "Why do we have a baby thermometer?"

"Because you're an infant with a high fever." Sam responded.

Dean smirked, pushing his sweaty hair off his forehead.

"But seriously, man, " Sam began, "What's going on? That wasn't your normal delusional."

"Wow, 'normal delusional'. Thanks, Sam."

"I mean that wasn't just the fever. What were you seeing, Dean? I've been with you long enough to know when you saw something that freaked you out and nothing was there, man."

Dean sighed and stuck out his arm, showing Sam the mark, "I think it's the mark. It's been burning since I got it, which was fine but then I started... Seeing things. And... And _thinking _things that're... You know, a little more fucked up than usual."

Sam nodded, and pressed further, "Like what?"

"Sam-"

"Dean, you can drown your feelings and your anger and pretend you're fine, and I can't really stop you but when the hallucinations and fainting spells start, I gotta know what's going on."

Dean swung his legs over the side of the bed, leaning forward slightly to face Sam, "I was seeing blood all over the bunker, y'know like some Danny Torrance type of stuff, and... Then bodies... And then I kind of just... imagined myself killing people... you know strangers and then..." He swallowed, closing his eyes, he watched himself stabbing Sam again, "And then it was over."

Sam stared at his brother, taking it in, knowing he'd left something out but Sam decided not to press anymore.

"Did Cain say anything about the side effects of the mark?" Sam asked.

Dean gave a cool chuckle, "Uh... I mean, he said, 'great burden, great cost' yada, yada, but I was just thinking we gotta gank Abaddon so I just agreed."

Sam exhaled heavily through his nose, looking frustrated.

"You took on the power of the father of murder without even reading the warning label?!" Sam's voice was rising, "You're just running at this thing blind, Dean, how could you be so-"

"Sam, hey, calm down-" Dean said, closing his eyes, bowing his head in pain, "I know, I know I'm a stupid bastard but can we talk about this later my head feels like it's about to collapse in on itself."

Sam opened his mouth to retort but stopped himself. Bitching at Dean for not taking the mark seriously was always an option for after his fever went down, but at the moment it seemed a little cruel. Dean was rarely sick and even if this was so arrogantly, somewhat unintentionally self-inflicted, Sam had to take care of him. Like Dean always had for him- like he had with the trials.

"Alright, why don't you try and get a few more hours of sleep."

Dean turned over, pushing his face into the pillow, muttering into it, "Why don't you try and shut up."

Sam rolled his eyes and got up to leave, turning off the dim light before he shut the door.


	2. Chapter 2

_*A lot of dialogue in this chapter, sorry, but there's more to come. I really appreciated the support from the last chapter, thanks, and to whoever put the link to this on Tumblr, **fucking thank you! I just happened upon it while browsing the mark of Cain tag and it made my whole day! **Anyway, read and review._

* * *

The laughter from before was echoing across every wall in the bunker, traveling down every corridor. It was that that woke Sam.

He'd gone to bed, knowing from experience that he couldn't help Dean if he himself was exhausted, and he assumed Dean would be safely out cold for another few hours- wrong.

His eyes snapped open and he was instantly awake and alert. He slid out of bed, started cautiously down the hallway, he called out,

"Dean?!"

Only manic laughter responded. A sharp kind of horror clutched at Sam's heart the further he went as he realized his brother's already questionable sanity was unraveling at an alarming rate and there was nothing that could be done about it.

"DEAN?!"

The laughter was definitely coming from the armory and Sam began a silent prayer in his head that his brother hadn't done anything he couldn't deal with.

He sucked in a breath and pushed open the door slowly so as not to startle his potentially armed and dangerous brother.

Every canvas covering over every box was ripped down the center by what was undoubtably a serated knife. Writing was carved into the walls and Sam hesitated for a moment, taking the time to read some of the scratches:

_Kill Kill Kill Kill_

_Cain killed Abel, Abel was saved, Cain was damned_

_Murder Mur_

It trailed off here, a long carved line leading the cut off word to a new text that read:

_I CAN'T STOP MYSELF_

Sam felt tears sting at his eyes but they were blinked back when he jumped when he saw a movement to his left from behind a shelf. Dean wandered out, holding out his arm to show Sam. It was bleeding heavily from cuts surrounding the mark, all the same cut as the ripped canvasses.

"Sammy?" Dean asked, sounding lost but also sick, his voice slurring.

"Dean, what did you do?" Sam demanded, approaching slowly.

"I tried t-to cut if off. Di'nt work though."

Sam reached for Dean's arm to examine the damage and dropped it at the light touch.

"Dean, you're way too hot."

"Aw. Thanks, Sam. I always knew some day you'd accept- hey, hey, ow!"

Sam had grabbed Dean by the arm and was dragging him out of the armory. His older, slightly smaller brother struggled against him to no avail.

Out in the main room, Sam pushed Dean into a chair and knelt down in front of him. He grabbed Dean's forearm and extended it, ignoring Dean's wincing as he did so. He crossed to the room to the kitchen where he grabbed their first aid kit and then returned to Dean who he was a little surprised to see had stayed put.

He took Dean's arm and examined the surprisingly deep gashes that circled the mark but didn't touch it. Sam set down the bottle of whiskey in front of Dean and started threading his needle. He started stitching Dean's arm, slowly, carefully, afraid of what his brother might do next.

"Aw, piss off." Dean said, glaring over Sam's shoulder.

Sam looked back and saw nothing. He'd dealt with Lucifer long enough to know what was going on, he recognized the darting eyes, the stoney quality of them.

"What're you seeing, Dean?"

Dean ignored him. Continued to address the apparent character standing by the door.

"There's nothing wrong with me, alright? It's a fucking brand, every Frat boy in the South has one, it isn't doing anything to me."

Sam pulled at Dean's wounded arm, trying to get his attention back.

"Dean."

Dean turned back and looked at Sam, then almost immediately shut his eyes, tight. He looked like he was about to have an aneurism. He bowed his head, scraping his fingers against his scalp as he combed through his sweat-soaked hair.

"Not him. No, no, no. I'll carve apart any son of a bitch, gut them, strangle them with their own intestines... But not him..."

"Hey! Hey, Dean-"

Dean pushed Sam away weakly, stumbled to his feet, trying to get away, he fell to his knees.

"Dean!"

"I can't kill him, I can't. I won't..."

It looked like he was having a nightmare, but he was still semi-conscious.

"Dean, talk to me!"

His eyes fluttered open, unfocused and confused.

"Sam?"

"Oh, thank god."

Sam hauled Dean to his feet and returned him to his seat at the table. He pushed back Dean's hair on his forehead, feeling the extreme heat and he pulled the baby thermometer out of his pocket.

Despite the apparent fit he'd just had, Dean seemed to be recovering his demeanor quickly enough. Though still exhausted.

"Stick that in me again and I'll shove it up your ass, Sam." Dean argued but it was tired, halfhearted, struggling to remain present.

Sam ignored him and held the thermometer in his ear until it beeped.

"Shit, it's went up, it's 104 again, Dean, we gotta go to a hospital before your brain fries."

"Please, like they'd know what to do." Dean said, gripping the back of the chair in an effort to stand up.

"Hey, hey-" Sam stood up, taking Dean's shoulders, "Where are you going?"

"Ice bath, man, I gotta get my head on straight so we can find us a hunt."

"Woah, woah," Sam said pulling him back by his arm, "First, sorry but I'm at least gonna be nearby the bathroom, you'll pass out and drown in the tub."

Dean rolled his eyes, turning away, unconsciously clutching the burning mark.

"Second, what the hell would we be looking for a case for?!"

Dean turned on Sam, though his menacing mask was a thin veil and it was not overly convincing considering the heavy flush in his face and there was still a film of sweat over his face.

"For God's sake, man, if I don't kill something soon I'm gonna hurt somebody!"

Sam nodded, sighing in that very typical irritated Sam way.

"Okay. I hear you. But what if... What if you start hunting, killing things, and then you start killing people just-"

"I know what I'm doing, Sam, I know what's going on-"

"No, Dean, you don't. You're sick and you're violent and I can't let you go off feeding this-this thing."

"Sam, if I don't kill something, I'm afraid I'm not gonna be able to control myself."

"Control yourself from what?" Sam asked quietly.

"From hurting you." Dean said.

There was a long pause and Dean continued,

"I'm rabid, Sam. This is my last swing at this thing but if I can't get a handle on it..." He broke off, and Sam waited with a grave looking apprehension, "I'm gonna have to clean up my mess and kill the monster... I mean, that's what we do, right? Kill monsters?"

He extended the half-stitched wound that was encompassing the glowing mark.

"I'm a monster, Sam."


	3. Chapter 3

_* I didn't even mean for this story to leave the bunker, but don't worry, there will still be plenty of sick/Cain!Dean. Just in a different location temporarily. Thanks for the continued support. **Read and**_** review.**

* * *

"JESUS, FUCK-!" Dean shouted, emerging from a few seconds under the freezing bath water.

Sam grabbed Dean by the front of his soaking wet shirt and pulled him up to his feet. Dean wavered weakly in his arms and Sam quick pulled him out of the tub before he could pass out. He forced him to sit down on the ground, back against the door, and patted his face lightly as Dean's head lolled to the side.

"Dean! Dean, c'mon, wake up, man." Sam said with a light air of urgency in his voice.

Dean blinked his eyes open and groaned. He ran a hand through his spiked, wet hair and spat some water at the floor.

"Well, that was fun." he said, glancing down at his stitched up arm where the mark seemed to have returned to it's darkened flesh color and it wasn't burning anymore.

Sam gave a nervous half-laugh and patted Dean's shoulders gruffly, grabbing a towel off the rack, he handed it to Dean.

Dean clambered to his feet, wrapping the towel tight around himself, he stumbled out of the bathroom, Sam following close behind, just in case.

Had he not been so worried he might've laughed at the fact that he was feeling a little more hulkish than usual, towering behind his hunched over, dripping wet, older brother. And this sickly, shorter person was battling homicidal urges and had an inherited the mark of the father of murder. Funny world.

"Alright, I'm gonna go change and start checking the news pages for-"

"No, no, I'll do the searching," Sam began, gesturing towards the hallway to the bedrooms, "You go take some aspirin and a nap and _then_ we can go hunt."

Dean glared, "You know Cain _killed _Abel?"

"Go to bed."

* * *

With a temperature of ninety-nine and a growing restlessness that was leaning more towards violent agitation, Dean was ready to go the second Sam said,

"Possible Shifter in Louisville. Father and respected handyman around town goes on a killing spree, cops can't find him but they _did _find pieces of his skin, some nails, etcetera, etcetera... Now, another guy snapped and he's missing, but," Sam glanced up from his computer, "They caught him on a nanny cam in one of his home invasion kills, there's a glare in the footage."

"Yeah, sounds like our kinda thing, let's go." his duffel bag was already in his hand, not even looking at the screen as Sam turned it around to show Dean the video.

Sam sighed, closing his laptop, "Dean, are you sure this-"

"It's the only thing left I can think of to do." Dean said.

* * *

It only took a few hours in Louisville to confirm it _was _in fact a Shifter, the freshly shed human flesh, the lens flare in the dark room in the video tape, witnesses all confirmed it looked _exactly _like their apparently recently corrupted loved one. Telltale signs of a shape shifter, and it wasn't long before Sam and Dean had narrowed down the playing field to the next victim's house.

They sat outside of it in the Impala, Sam loading his gun with silver bullets, while Dean had opted for a silver knife instead. Sam felt concern gripping at his heart as he watched his brother, watching the house intently, that mild gleam of red beginning to come out in his iris again. Sweat was beginning form a thin film over his face, his breathing seemed to be becoming labored.

Sam reached over to check Dean's temperature again but Dean turned on him, snapping,

"I am _fine_, Sam, do not even try to take me off this right now-"

Dean glanced up suddenly, and Sam's eyes followed suit. There was movement by the fence on the left side of the house near the trees that surrounded it. Someone had climbed over it and was creeping in through the side window.

Dean had jumped out of the car in an instant, staggering like a mad man, knife wielded as he made a b-line for the front door. He heaved his body against it, trying to break it down, but it was fairly sturdy.

"Dean!" Sam hissed, trying not to draw any unwanted neighborly attention.

He got out and headed after Dean who had kicked in the door already.

"Dean! Stop, listen-"

Dean burst into the house, glanced around the front room, and started running up the stairs. Dean was hearing the laughter again, saw images of himself carving apart this shapeshifter in his head, but luckily, it was all inside his head.

At the top of the stairs, he saw a bedroom door slam and he broke that down too. A woman was tied up in a chair, mouth duct taped but she was struggling to scream against it. Dean heard yelling, heard the voices of the two men he saw before him, saw one move towards the woman and was on him in second.

The voices were distant and difficult to understand in Dean's ears but he didn't need to hear this thing to kill it. His blade grazed the man's arm and he heard Sam's footsteps behind him and then his voice, loud, booming in Dean's head with a sudden clarity,

"THE OTHER ONE, DEAN!"

Dean dropped the guy he had, his vision was strangely unfocused. He stumbled over to the other guy and managed to stab him in the chest, killing him.

He heard the voices that were yelling distantly again, echoing, and he had to get away. He covered his ears and staggered out of the room. He tried to run out the door but all he managed to do was trip and collapse on the front sidewalk. His skin felt like it was on fire and it was all radiating from the Mark.

The voices were fading out and everything went black.


	4. Chapter 4

_*Next chapter, hope it suffices. Sorry for that last cliff hanger. This one kinda comes with another one. **Read and review.**_

* * *

The thrill of stabbing the Shifter hadn't been strong enough. Even unconscious, Dean's mind still raced, never stopping, never really resting because he hadn't satisfied his craving.

His head had mostly stopped pounding at least, but as he began to pull through the darkness, he started to panic remembering where he'd passed out. He certainly wasn't there now and they'd made enough noise to potentially draw the attention of local law enforcement.

He was exhausted, his whole body screamed for a peace of mind and a long nap. But the violent, somewhat twisted images that flicked through his mind forced his eyes open.

He blinked, his vision a little fuzzy, and a mild relief passed through him as he realized he wasn't in prison, he was in the motel. He started to sit up just as Sam came in the door. Dean felt a sudden need to apologize for his overzealous approach killing the Shifter.

"Sam." Dean began, but he trailed off, unable to explain his behavior from earlier or even account for what happened between then and now.

Sam shut the door behind himself and stowed his phone in his pocket, sitting down on other bed.

"Who were you calling?" Dean asked, unable to word what he'd really wanted to say.

"Crowley. No answer though." Sam said, "Now, are you gonna tell me what the hell happened in there?"

Dean shrugged, swinging his legs off the bed as he sat up completely, "I don't know. I got a little impatient and I just wanted to do it already, man, it's not a big deal-"

"Yeah, no, I got that part," Sam said a little harshly, "I mean you cut that guy, his skin didn't burn when the silver touched him, you knew the other guy was the Shifter. You almost killed that guy, Dean."

Dean blinked. He hadn't known that. Had he? Being honest with himself, the word Shifter had somewhat escaped his mind in that moment. He just wanted to stab it. End it. But how could he explain that to Sam that, no, no, he was in control of himself, he could be trusted, except when he couldn't, which was just whenever his homicidal mind got a little restless?

"I don't know, Sam. But I am going to get a handle on this, okay?"

"I get it, okay, you can't control it, believe me, I get it, but I can't trust you if you can't trust yourself."

The phone rang and Sam sighed heavily before answering, "Agent Young."

Dean felt that deep seeded homicidal rage inside him stirring. _Stop it_, he told himself, _you are in control_. But he wasn't.

"Another one? Alright. Thanks." Sam said, hanging up, he turned to Dean, "There's another Shifter. The first guy, the one who went missing? They caught him on tape robbing a bank. All the tellers are dead."

Dean wanted to bolt and track the thing down. Carve it apart; slow, painful death. But he had to hide it. Put a mask on the monster so he could pass as a human.

"You sure this one's a Shifter?" Dean asked, praying Sam would say yes.

"Yeah," Sam said and a sick satisfaction bubbled in Dean's heart, "The same lens flare on this video as the last one. Cops think the guys are using a jammer to mess with the footage."

Just go, that's enough for Sam, go, kill it.

"Could it be?" Dean asked, biting the words as they were forced through his teeth.

"I doubt it. Interference looks more like snow than a glare." Sam stood up, "Alright. I'll take care of it, I'll be back."

"Woah, hey!" Dean said, "You can't go alone and I can't just sit here-"

"I can't let you hunt like this, Dean." Sam said, but he sounded more subdued, almost broken.

Dean could hardly care though.

"Try and stop me."

* * *

Sam handcuffed Dean to the bed.

"Kinky, Sam." Dean said, shaking his wrist in the cuff, testing how strong the hold was.

"I'm sorry." Sam said, and it was genuine, and then he left.

Dean watched him go. Knew he shouldn't be mad at him, he was doing exactly what Dean would've done, put in the same situation. Hell, he _had _done this same thing in a similar situation. But there was still that sharp voice in his mind that said, _he thinks I'm a monster._

"I _am _a monster." Dean reasoned as the voice seemed to manifest itself before him in the form of the black eyed self he'd so often dreamed about.

"_You're not a monster. You're stronger. You're a legend._"

"What the hell are you even talking ab- No, I am not about to have a conversation with someone that isn't there, alright? No."

"_You know how to pick the lock on handcuffs, Cain. You have a knife in your pocket._"

Dean wondered why he hadn't thought of that initially and took out his knife. He looked around for something to work at the tiny tumblers inside the handcuffs while the knife held the lock in place. His eyes focused on a bent up strip of aluminum next to him on the floor, separating the bathroom floor from the bedroom. He grabbed it and peeled off a strip (not the highest quality material, although it was just a threshold in a dirty motel) and picked the lock, getting himself free.

Fighting hard passed the bloodlust that dominated Dean's brain was a voice he recognized as Sam's. It might've just been a voice in his head, but it had the same tone that Sam had that made him feel guilty when he knew he was doing something wrong but refused to stop.

_"Sam told you to stay here to keep you safe. And himself. From you."_

A sudden surge of rage hit Dean's uneasy mind and he stood up, now free of his handcuffs he grabbed the lamp off the side table and threw it at the wall.

"I WON'T KILL HIM."

_"Cain killed Abel, Cain killed Abel..._" The voice sang in his head.

Dean stopped himself from responding out loud. Bit back his anger, tried to get a handle on his breathing and gauge a certain level of sanity.

_"Cain had to kill Abel."_

With that last thought, Dean bolted. Out the door, knife in his pocket, he headed for the bus stop, knowing Sam had taken his car but even that didn't seem to matter to him anymore.

* * *

Last the Sheriff had talked to him, Agent Young was heading for the sewers where a witness had seen the suspect disappear into after fleeing the bank. Dean gave a nod of thanks and turned to leave the station when the Sheriff said,

"By the way, Agent, you might wanna take a day, you look like Hell warmed over."

Dean gave a sarcastic, but more manic sounding, "HA." and left.

* * *

The Impala was parked in a small parking lot right by a large sewer hatch. Dean checked his surroundings for potentially curious passer bys and seeing none, he opened it up and climbed down. He knew immediately this was the Shifter's newest hideout because two yards down the giant pipe he found a lump of human flesh and a few fingernails.

By the time the pipe opened up into a small underground, cavernous area, the Mark was burning again and Dean prayed Sam hadn't killed the Shifter already because Dean _really _needed it right now. He felt addicted. And an addiction to murder can be a tricky vice to succumb to. He stepped out into the dim lighting of the room and heard a familiar, muffled yell.

He turned the corner and found Sam tied up to a pipe, mouth duct taped. Dean felt the Mark heating up and tried to ignore when he heard Sam's voice from behind him say,

"No, that one's the Shifter, I got him tied up," Dean turned around and saw Sam walking towards him, "I was worried about what you said so I thought I'd come back and get you so that you could kill him instead."

Dean looked from the tied up Sam to the free, talking Sam.

_"Cain killed Abel, Cain killed Abel..."_

_"Cain had to kill Abel."_


	5. Chapter 5

_*I don't know when these cliff hangers are gonna stop. I'm kinda just doing this as I go, I hope I'm disappointing any of you. I had no idea where this story was going until I started adding more. Thank you for all the rad reviews so far, I appreciate your readership. **Read and review.**_

* * *

Dean took a few steps back, pulling out his knife as the Mark heated up on his arm.

"Woah, woah, Dean." Standing Sam said, "You okay? You look a little... Homicidal."

Standing Sam gave a nervous kind of half-laugh that Dean knew very well to be his but he also that a Shifter would have no problem duplicating it. He raised the knife threateningly at standing Sam.

"You're not my brother."

He started towards him, knife shaking in his hand, eyes set dark and hard.

"Hey, hey, easy to test that. You know the drill, cut me and see if I burn but..." Sam raised his hands cautiously, "I think maybe you shouldn't because your perceptions haven't been particularly uh... reliable, as of late."

Dean felt his head starting to swim, the desire to kill sending heat sweeping through his body in violent waves. He was sweating again, and starting to shake, despite this. He raised his own hands, and moved slowly towards tied up Sam. He removed the tape from his mouth.

"Don't listen to it, _I'm_ me, Dean, go ahead and cut me," he exhaled heavily through his nostrils and said, a little softer, "But I think it's right. I don't know if you'll see what's real."

"Alright, I don't have time for this." Dean said harshly, and he sliced tied up Sam's arm and watched through focusing and unfocusing vision as the the skin surrounding the fresh cut burned.

Dean looked up at the face of tied up Sam, but he didn't wince. Just nodded and said,

"See?"

"It burned, you saw it burn, don't let this thing mess with your head, Dean." Standing Sam said as he approached.

"Just-Just hold on, stay there." Dean said, standing up and pointing the knife warningly at standing Sam.

He cooperated and raised his hands in surrender again. Dean wanted nothing more than to just kill one of them. _Either of them_. No! Not either of them, not Sam, never Sam. _Either_. No, God, please, no. _Both of them_. I'm not killing Sam! Cain didn't have to kill Abel. _Abel was going dark side. Sound like someone we know?_

"Dean." Standing Sam said nervously, watching Dean with a familiar kind of concern in his eyes.

He stepped forward and standing Sam backed off a little. Dean grabbed his arm and cut him. That burned too.

"I'm not a Shifter." Standing Sam said.

"Dean, you know what you saw, it burned, please." Tied up Sam pleaded.

"Just-Just shut up, both of you." Dean said shakily.

His bloodlust was pounding hard against the inside of his skull and he just wanted to know. Just wanted to be certain that he was not going to kill Sam. His vision was tilting from side to side, blurring and clearing and all he could do was pace and try not to fall down.

His fever was spiking again and he knew it but he couldn't pass out now, he couldn't fall into a hazy state of delusion. He had to stay sharp because even fully healthy, identifying the difference between the real person and the Shifter imitating them was a tricky job. If it wasn't for the burning cuts they'd be impossible to distinguish the difference between them, and now Dean was too uncertain of his own sanity to be sure which really burned.

"Just kill both of us." The standing Shifter said.

"No! Dean, I read about the Mark, you kill your brother, you go to Hell, you become a demon, like Cain did-"

Dean stopped pacing. He couldn't think, his brain was about to melt. His entire system was so completely fried that he couldn't trust himself to decide who was telling the truth. But on the other side of things a voice told him the only way to clear his mind would be to kill. Properly.

"Just do it, there's no other way-"

He covered his ears, bowing his head in pain. They wouldn't stop. He couldn't tell. Not for sure. And he couldn't kill Sam. _Won't. But you can._ LEAVE ME ALONE.

"He's fucking with your head!"

_There's no way out. You're either going to have to make the choice. A fifty-fifty shot of killing your brother or the Shifter. Or you can skip all that nonsense and kill them both. Imagine how satisfying __**two **__murders. To slow, painful deaths at your own hand and the power..._

"SHUT UP!" Dean screamed.

"Dean," Tied up Sam said slowly, "You need to calm down, that Mark is gonna kill you if your temperature goes up anymore-"

"Dean-"

Dean sank to his knees, his mind was being torn apart by a complicated combination of rage and confusion. He blinked, was seeing blood again. Two dead Sams. And nothing hurt more than that. _You can't imagine the amount of power it will give you, Cain._

Stop calling me that.

_Kill your brother and the fight between Crowley and Abaddon won't matter. You'll kill them both and __**you **__will be Hell's new king._

"Dean-"

He stumbled to his feet again and untied the Sam on the ground. He stepped back from the both of them. He raised the blade and looked at both of them. Met each Sams eyes and watched their faces carefully as he stabbed himself through the stomach.


	6. Chapter 6

_*Holy shit, this is hard, I'm so scared of disappointing you guys because you've been so rad throughout this story, but here it is, the next chapter, here's to hoping it's not complete shit. **Read and review.**_

* * *

Both Sams ran at him. Both yelled, "DEAN!" But only Sam who'd been tied up had tears in his eyes and genuine pain in his voice, and Dean knew.

Shifters were good but it's difficult for anyone to perfectly imitate the reaction to your brother stabbing himself.

When standing Sam reached him, Dean ripped the blade out of himself and stabbed it through the Shifter's heart. And goddamn, did it feel good. He ignored the wound in his stomach, ignored the real Sam's concern, and half crawled over to the Shifter's sprawled out body.

He yanked the knife out of its chest and in a sudden surge of rage he raised his arm and stabbed again. And again and again and blood was splattering all over his face and his arms and he didn't care and he didn't stop until the real Sam pulled him away.

"Dean, please..." Sam begged, holding Dean's arms to his sides.

Dean stared at him through a scarlet fog and found himself lost in his bloodlust. He was looking at Sam but the fact wasn't registering. He just saw a fragile meat suit full of blood and bones.

"Dean!"

He heard the voice but still it made no difference. He felt powerful. It didn't matter that the fever would leave him weak and helpless because each time he killed he got stronger, and soon the fevers would be nothing to him.

"DEAN!"

The urgency and the fear in Sam's voice were what finally shook him. The fear. Fear for Dean? Or fear _of_ Dean?

He looked up at Sam, almost feeling the red draining from his eyes (not unlike it was draining from his stab wound) and he tried to pull off the mask. Be human. _Barely_. SHUT UP.

"Sammy?" He said, finding a comforting humanity in the nickname and clinging to it, "It's okay. Everything's okay."

Sam watched his brother return to himself and sighed deeply, pulling him into his chest, hugging him. Neither cared about the dead Shifter and for those few seconds, neither cared about the profusely bleeding gash in Dean's abdomen. All that mattered was that Dean knew his brother, and he wasn't going to kill him.

Sam took Dean's shoulders and examined him at arm's length, trying to ascertain the damage. But he was distracted by the quick loss of focus in Dean's eyes as the blood loss hit him. He was falling limp in Sam's arms.

"DEAN!" Sam yelled, shaking him gruffly, "Dean, c'mon, stay with me here, man, I'm gonna stitch this up, it's gonna be fine..."

Dean blinked, looking woozy initially and then his eyes found purpose and they dug razors into Sam's heart as he looked up at him. The red glint was back and encircling his entire iris.

"_Either_." Dean said, his voice low and gravelly, but very intentional.

"What?" Sam asked, that fear starting to creep back into him.

"I needed it, Sam." He said, a twisted smile cracking across his face, "I needed to stab that fucking thing. But it didn't have to be the monster."

He laughed. And Sam didn't know what to do. He was afraid to do anything. He spoke with caution.

"Dean?"

Dean laughed again, manic and dark.

"_Cain._"

The laughter eventually died out, and slowly the red in Dean's eyes ebbed away until they were green and vulnerable. His eyes traveled down to the cut on Sam's arm, and through blurring vision he saw it fizzle and burn.

"No, no, no, NO! GODDAMMIT!" He shouted, sinking from Sam's grasp.

He collapsed in on himself, one hand held firmly on his own wound, the other gripping his hair as he shut his eyes in pain.

"Fuck, fuck, fuck, no... God, no..." Dean whispered, anguished but slowly losing the ability to feel at all, the idea of him killing Sam sent a cold numbness through his body.

"What?!" Sam asked, terrified he pulled Dean up to look at him again, "What are you seeing?!"

"I killed Abel." Dean said in response, obviously less coherent than he'd been just moments ago, "No, Sam. I killed Sam."

Sam looked down at the cut on his arm and saw it for what it was, a thin slit and nothing more. Nothing burned, nothing but a bloody line.

He looked down at Dean and saw he was pretty much out at this point. He might've passed out from blood loss, maybe over exertion, maybe a hundred things, but it didn't matter. Sam couldn't bare to watch him struggle with delusions that seemed to injure him so severely, whatever they might be exactly.

He stood up, picking up his older brother. And carried him out of the sewer, and back to the Impala.

* * *

Dean woke up, for the second time that night, back in the motel. The kill seemed to have caused the Mark to ease up a bit; it wasn't burning any more and though still a little dazed, Dean was sure his fever had gone down somewhat. He pulled through the dark, feeling a sharp pain in his abdomen as he did so. He reached down to feel it and found a great deal of gauze he didn't dare venture beneath. He sat up slowly as he blinked his eyes open, regaining awareness gradually. The first thing he saw that registered was Sam.

He was sitting at the table on his laptop. Dean felt a pang of guilt for putting Sam through all this but also took it as a good thing that he could feel anything at all at the moment. His movement seemed to stir Sam who looked over and immediately got up and made his way across the small space.

Sam opened his mouth to say something but Dean cut in. He'd prefer to skip over all that 'how're you feeling' crap any how because it would only make him feel like more of a bitch.

"Sam, listen," he said, and his voice sounded strangely low and scratchy to his own ears, "I'm really sorry. Okay, I know... I should've maybe read the fine print before I signed off on this whole thing but, hey, I'm in it now. So, I mean I guess we can't really do anything about it but... I just want you to know I'm sorry."

Sam nodded, accepting it, and then he said,

"I get it. I can't exactly preach, I mean, I've jumped into some pretty stupid situations myself and I guess..." He looked at Dean with those puppy eyes that he used so often, "I'll have try and help you. Even if you won't let me."

Dean sighed, "Sam, you saw how I was, I could kill you. Hell, I'm _supposed _to kill you, if we're going by the original book, I mean, you said it yourself, you can't trust me if I don't trust me, and I don't. At all."

"Well, I believe in you."

Dean laughed, pushing his sweaty hair off his forehead as he swung his legs over the side of the bed, "I'm saying I might kill you and you _believe _in me?"

Sam shrugged, "Hey, what else can I do? You're my brother and I personally don't think you'd do it. Sure you could, but I don't believe you will."

Dean rolled his eyes, getting up and crossing the room to the counter the whiskey was sitting on, "Yeah, well keep talking like a pansy and maybe I'll change my mind."


	7. Chapter 7

_*I am **super sorry**, I had not been prepared at all to write this chapter, I didn't plan it out this far I was just going with it, I hit a dead end and then got distracted, started watching The Originals (great show, right?) and excuses, excuses, I am super sorry. _

_The second part of this chapter is set after "Blade Runners" because I feel like a story about the effects of the Mark of Cain needed the effects of the Blade too. _

_I might add one or two more chapters after this but I am so sorry I didn't update sooner. Deepest apologies. **Read and review.**_

* * *

The drive back to the bunker was exceptionally awkward. Sam drove as Dean, now aware enough of his surroundings to realize how much his stitched up wound hurt, was drinking heavily and in these circumstances, Sam would silently get behind the wheel and Dean would not protest. However, Dean wondered if maybe he should drive because Sam was very rarely looking at the road and more often glancing over to check on Dean.

In an apparent submission to his potential death by distracted driver Sam, Dean laid back in his seat and shut out the world and slept.

_"You and I are very much alike." _Cain had said, and the memory echoed in Dean's subconscious as he dreamed.

_"Yeah, except I didn't kill my brother."_

_"You saved yours. Why?"_

The question was surprisingly harder to answer than he had anticipated. He wanted to respond immediately, felt like he could. But it took him a minute to finally retort lamely,

_"Because you never give up on family."_

You never give up on family? What did that even mean? You continuously give up on family, just let something go that you shouldn't and move on. That's the exact opposite of not giving up.

_"Where's your brother now then?"_

Dean remembered how he'd felt a painful pang of regret. Why had he left Sam? Oh, right:

_"I'm poison, Sam. People get close to me, they get killed- or worse. "_

It was true. And with the mark burning tenderly on his arm it was only becoming more and more true. Abel-dammit- _Sam_ wasn't safe with him. The natural pull towards murder he felt now was going to endanger anyone and everyone he encountered. He wondered if maybe he should take off again. Just to make sure he didn't lose control and do something he couldn't fix this time.

_"You never give up on family."_

Yeah, well, Sam's long since given up on me.

_He's been pulling you back whenever you've gone all Patrick Bateman on him or someother innocent since you got the mark. He cares._

He can care. That doesn't mean he hasn't given up. He knows.

"Dean."

His eyes snapped open and he felt Sam's hand gently hitting his shoulder as he woke up.

"We're here."

He sat up in his seat, regained his bearings and shook his head clear of thoughts of Cain and Abel as he followed Sam into the bunker. And for now he felt the near attempt on his brother's life would tide him over until the next attack of Cain.

* * *

**WEEKS LATER**

The mark burned but Dean was barely aware of it as he fell deeper and deeper into the rabbit hole of his homicidal mind.

_"I can give you the mark, Dean, if it's what you truly want."_

_"What?"_

_"The mark can be transferred to someone who's worthy."_

_"You mean a killer like you?"_

_"Yes."_

The mark seared its way across his forearm as it branded itself there when Cain had given it to him. But even then the feelings of rage and aggression were more difficult to overcome.

These feelings had slowly retreated back into his mind only to creep back unexpectedly and fill him with a bloodlust that felt so normal to him now.

_"You'll get used to the feelings. Even welcome them."_

The emotion that shook Dean's mind and soul when he held the First Blade was even stronger than the mark. He couldn't decide whether it was better or worse but the feelings of rage and aggression had been replaced by an emotionless bloodlust that stripped him of the fear the mark brought on.

That is, until he let it go. When he dropped the blade the fear of the complete lack of moral control he'd just felt hit him hard. He felt so mentally, emotionally, and even physically weak in comparison, or perhaps because of, the unimaginable power the Blade had given him.

The weakness he felt without it was almost unbearable. His hand shook, desperate to hold the Blade, desperate to feel that powerful control that a lack of thought control brought him.

He didn't think in emotions and rationale, he just thought in killing. The strategy, the practice, was unnecessary now that anything he wanted to kill was going to die. He couldn't miss unless he wanted to.

His hand shook, his eyes stared out into space, seeing only peaceful, bloody red.

"Dean?"

He snapped back into reality as Sam suddenly walked into his line of vision.

"You okay?" He sounded genuinely uncertain and the worry was evident in his tone.

Dean blinked, cleared his throat, "Yeah. Yeah, I'm fine."

Sam stared at him, he knew he was lying to him and the concern only etched itself deeper into Sam's furrowed brow bone.

"You're sweating." Sam said flatly.

Dean hadn't been aware of this. He touched his forehead gingerly and his fingers came off with a dab of moisture clinging to each of them. Not to mention the fire that was growing inside his head.

After his run-in with Magnus and his first time holding the Blade, the effects of the Mark seemed to have gotten worse. He wasn't afraid of what he was becoming, he was afraid of what he already was. The second the Blade hit his palm he felt a familiarity but also a more potent strength than he'd experienced before with the rage that embodied him.

He felt like a twisted combination of how he'd been after he'd lost John, and he felt the power and the sickness of himself as a torturer in Hell, and he felt the purity of his kills in Purgatory, but worst of all he felt himself beginning to understand the person Zachariah told him he would become in 2014 if Croatoan and the apocalypse began again.

In fact, next to how he felt now, the soldier of a man he saw execute his own friend in cold blood because he might've eben infected, looked like a logical, upstanding citizen.

"Dean-"

"I said I'm fine, Sam." Dean said, wiping the sweat off his head, an uncontrollable fury stirring inside him, "So, I run a little hotter now and I get a little twitchy. Hey, at least I'm not firing weapons at an invisible Satan or drinking demon blood."

He knew it was entirely uncalled for. He knew he was completely in the wrong and that he should apologize because it was his own fault, and his alone, that this was happening to him. If he'd let Cain explain what was going to happen, he might've been able to control some of this. Or maybe he might not've accepted it.

But Sam just scoffed, in that obvious attempt to cover how hurt he'd actually been. And he walked off, glancing back at Dean with worry etched clearly into his face.

Dean picked up his whiskey glass and hurled it at the wall Sam had just passed.

_Why am I doing this?!_

He couldn't control himself. And the familiarity of the feeling was beginning to make him think this might not just be the Mark of Cain or the Blade that made him like this.

He'd always been a monster.


	8. Chapter 8

_* I should've ended this earlier and cut my losses, now I'm just sorta writing what seems right and hoping for the best so, hopefully, enjoy, I'll understand if you don't though. **Read and review.**_

* * *

Sam's eyes snapped open as he heard a muffled voice from far away invade his subconscious.

He sat up, wondering if this was a dream or if he was going crazy now too. However as he climbed out of bed and headed for the door he realized the voice was real and it was being carried from another room through the vent.

He laid flat on the floor, pressing his ear to the grate and with a pang of worry he realized it was Dean's voice. Sam listened closely.

"No, we found Ginger, just bring the- I don't have time for this, Crowley, are you bringing it or what?"

Sam stood up. That was all he'd needed to hear. As far as Sam was aware, they had no idea where Abbaddon was.

He knew that judging by the placement of the vent and the set-up of the bunker, this vent likely led closest to the dungeon directly below him. Proceeding with caution, Sam made his way down to confront his borderline psychotic brother. He entered the dungeon and found Dean was on the phone, presumably talking to someone real.

"What do you mean she's not here?! Dammit, Crowley, there is a red-haired demon bitch just waiting to be ganked. You coming or-"

It seemed at this point that Crowley had hung up because Dean pulled the phone away from his ear and threw it at the wall.

"Dean?" Sam asked nervously.

Dean didn't give any sign that he recognized that Sam had spoken. He was visibly shaking, starting in his hand and spreading through his body.

"Dean." Sam repeated.

Dean looked up be he had that dead look in his eyes that seemed to take him over every time he killed. The Mark burned, white hot and glowing. Dean began to reach slowly for his knife when an audible knocking cut through the silence and effectively snapped Dean out of his trance.

The voice from upstairs and outside the bunker door seemed amplified, and knowing the demon who the voice belonged to, it probably was.

"Singing telegram!" Crowley called.

Dean turned and looked at Sam uncertainly.

"C'mon, I've got a certain jaw bone, previously owned by a-"

Dean had left the dungeon as fast as he could without running as the Mark burned brighter. Sam followed him up to the door where he said,

"Dean, you told Crowley where the bunker is?!"

Dean ignored him and opened the door, letting the demon in.

"You got the blade or-" Dean was cut off when Crowley flicked his wrist and sent the jittery hunter tumbling down the stairs.

Sam pulled out his demon knife and was rounding on Crowley in an instant.

"Ah, ah, ah, Moose... I just wanna chat." Crowley said, waving his hand he threw Sam into the wall behind him and held him there.

Sam struggled against the force.

"Crowley, I am done-"

"I'm sure you've been having some concerns about Ted Bundy down there," he gestured down at the unconscious Dean, "And I'm just here to discuss it."

Sam nodded and Crowley released him. Sam stepped forward, swinging his arm back to punch him. But Crowley had snapped his fingers and reappeared down at the bottom of the stairs where he was checking on Dean and then waved for Sam to come help him.

"Give me a hand, would you, Jolly Green? Squirrel might not have your hulkish size but he's not exactly light."

Sam wanted to break the demon's nose, but he also knew that he was the only person who might be able to help Dean. So, he hurried down the stairs, took the majority of Dean's weight and hauled him into his bedroom.

Sam set Dean down on his bed and then turned around suddenly when he heard a metallic click. Crowley had handcuffed Dean to the bed, but on closer inspection, Sam realized they were demon cuffs, the spellwork etched in the metal catching his eye.

"What the hell, Crowley?"

"Precautionary. Let's take this conversation elsewhere, shall we?"

They walked back out into the main room where Sam rounded on Crowley again, seething but also desperate for someone to help his brother,

"What the hell is going on?"

"Settle down, moose, I can't say for sure because a certain someone skipped the terms and conditions- which you know is my favorite part-"

"Point, Crowley."

"But I have a few theories based on remarkably little research and a natural, extensive knowledge of demon kind."

Sam pulled out his knife again just to press Crowley to elaborate faster.

"Alright, alright- I think our friend, Dean is just a bit strung out."

"Meaning?"

"He's addicted, Sam. You know your psycho of a brother has always had a knack for killing, well, now it's his obsession and the Mark and the Blade give him the ability to kill quicker, with unmatched accuracy, and he can't get enough. It's just power, Sam."

Sam stepped back, pocketing his knife again, taking it in.

"Addicted?"

"You saw him, high off the sweet smell of a nice decapitation when he killed Magnus? And since I took the Blade back he's been calling me nonstop, pretending he's found Abbadon, just to get his hands on the Blade again? He's a junkie. Just like me. Just like you were. And eventually, it's going to turn him."

Sam nodded. Somewhere inside himself, he knew it was true. All the signs were there. He just hadn't wanted to accept that his brother had a passion for homicide or that there was something vaguely demonic stirring inside where it's been hibernating since he'd gotten out of Hell.

"So, what'd we do?" Sam asked, this more subdued than his last comment.

Crowley sighed, "I don't feel the new father of murder would take kindly to an intervention so I feel the only option left is to keep letting him kill until you find Abbadon."

"You want me to support this?"

"I want you to keep him from getting dangerous until Abbadon's six feet under and then we'll cut him off. Just give him what he wants until then or it's us he'll be hunting."

Sam scoffed, "All you care about is taking back your crown and you'll let Dean damn himself to do it."

Crowley closed in, looking somewhat menacing from half a foot below.

"I want my kingdom back so I can get the world back in order. I want things back the way they were. And I want to keep you and Dean alive because you're both of use to me, and, well, let's face it, we're all buddies, now."

"Crowley, we are not-"

"Friends. And you can deny me that in words all you like but we are on the same side here. I don't want Dean to turn into one of the black eyed scabs I order around but he's the only one who can kill Abbadon. So, we'll have to ride it out with him."

And with that, Crowley was gone, and after a moment's hesitation, Sam headed back to Dean.

* * *

Dean pulled through the blackness. He didn't feel like himself and he wasn't even aware of the fact. He blinked away the dark and began to sit up.

Seated in a chair by the door was sleeping, unsuspecting prey. He could kill it. It registered that the thing was Sam. His brother. And he felt the rage take him as memories flooded his head.

"_I'm stronger than you, Dean!" _

_Hopped up on demon blood? You call that stronger? ... _

_"You lied to me." I had to! You know that..._

_ ... _

_"Situation were reversed, and I was dying, you would've done the same thing." "_

_No, Dean. I wouldn't. Same circumstances, I wouldn't." _

_..._

"Dean. Hey. You okay?"

Dean blinked, Sam was in front of him now, shaking him gruffly. Dean hadn't even noticed he'd woken up. The concern in Sam's eyes was real and it was this that began to fight back the urge to stab him in the heart.

Dean nodded, and suddenly remembered the Blade.

"Where's Crowley?"

Sam sighed, backing off a little, "Gone. He didn't have the Blade."

"Lying bastard." Dean muttered.

Sam could've laughed at the irony of it considering the only reason Crowley came at all was because Dean had lied saying he'd nabbed Abbadon.

"What'd he want then?" Dean asked, sitting up completely and rubbing his aching head.

Sam hesitated. Uncertain what he could say.

"He's worried you're losing it and you're gonna end up going dark side instead of just ending Abbadon." Sam watched Dean for some reaction but found none, "But you can get a handle on this, right?"

Dean glanced up with that dead look settling in his eyes, "Who says I want to?"


	9. Chapter 9

* _I hope this chapter is acceptable, I kinda just keep adding on here as I hope it's not too atrociously unplanned. _**Read and review.**

* * *

They didn't see Crowley again for two weeks. Despite the not-so-secret desperate voicemails Dean left him claiming he had Abaddon, Crowley didn't respond.

Between moments of somewhat forced, normal Dean, the Cain side would creep to the surface. His obsession with tracking down the ginger demon only got worse between cases. Most nights he didn't sleep. And even when he'd disappear into his bedroom for three hours, Sam wasn't convinced he was sleeping then either. Not to mention Sam was sure Gadreel had said something when Dean was torturing him the other day that had gotten to him. But Dean just denied it and avoided the topic.

Since nearly killing Gadreel, Dean had apparently become aware and put in more of an effort to conceal everything from Sam. Tried to make the mask of sanity sit right on his face again.

But it didn't fit. Sam could see right through it: the dead, shadowed eyes, the restless extremities, and the obvious moments where he'd check out for a bit only to come back either more anxious or more manic than ever.

When Sam woke up, all was silent but for a constant, rhythmic thumping. No shower running, no coffee maker grinding, no keyboard tapping, just steady thumping.

Sam felt the cold fear grip his throat, he tried to prepare himself for whatever state Dean may be in, and then tried to convince himself he was being paranoid.

He stepped closer and closer to the sound, and found an empty whiskey bottle lying on the floor.

Great. Just the icing on the cake.

He rounded the corner and stopped.

Four more empty liquor bottles cluttered the desk, lying in a heap of research, more than likely on Abaddon.

Worse than the obscene amount of alcohol Dean seemed to have ingested was Dean himself. He was sitting, half collapsed in the corner and the sound of the thumping was Dean's head hitting the wall.

Repetitive. Steady. _Banging. His head. Against. The wall._

"Dean!"

If Dean had heard Sam, he didn't acknowledge it.

Sam rushed across the room, dropping to his knees beside him he grabbed Dean's shoulders and surveyed him carefully.

There was a superficial but fresh break in some skin on Dean's temple that leaked small traces of blood. His eyes looked dead, like they hadn't seen anything in a long time.

"Dean?" Sam repeated, worry making his heart pound each second of Dean's silence.

Dean blinked, looked up but he just looked lost for a minute as he regained his bearings.

"Dean, you with me?" Sam asked, not letting go of Dean's shoulders.

"It's not working. Nothing's working." Dean said, his voice was low, monotonous. Dead.

"What's not working?"

Dean gestured vaguely towards the desk, "I don't feel it. I don't feel anything."

Sam looked over at the empty liquor bottles and turned back to Dean, who continued,

"I can't sleep, and I can't get a buzz, I'm just sober and conscious and..." He trailed off, rubbing the Mark absently.

Sam wanted to offer some level of help, but what could he say? Nothing he said seemed to matter at this point, Dean was disappearing.

He turned suddenly, that cold stare flickering back Ito his eyes, "And you." He pushed Sam's arms off him, retreating into himself, "Pretend like you care. Pretend like we're fine. Pretend like I'm anything but the weak, pathetic, lonely brother you think I am."

Gadreel's words burned coming out but it hurt worse trapped inside. He knew why Gadreel had said what he did but that didn't make it less true.

"What're you talking about, Dean, I do care, just tell me what-"

"Always better than me. And still always screwing up. I mean, I do too but demon blood? Really?"

Sam wanted to punch him. He was judging him for drinking demon blood four years ago and he'd accepted the Mark of Cain, the mark of the beast. The worst biblical mark you could brand yourself with.

But he knew fighting back would do no good to either of them.

"Always God's favorite. Even when I got dragged to Hell to save you, still, Abel gets the VIP treatment in Heaven."

Dean was delusional or at least Sam told himself that.

He reached into his jacket pocket and pulled out his knife, pointing it at Sam.

"You won't be able to get hurt anymore. You'll be safe. No demon blood in Heaven. No Lucifer in Heaven. Not now, anyway."

Sam backed off slowly but as the trembling from Dean's hand spread through his body and the Mark burned white hot, he'd be damn near unstoppable.

"Dean!"

Dean punched him. Dragged him to his knees and held him by the collar of his jacket and then raised his arm, knife twitching violently in his hand.

Fear flooded Sam's mind when he closed his eyes, and worse than that his mind flooded with '_Dean, don't kill me_' when he opened them.

He was about to be killed by his brother, and while he might go to Heaven, Dean would have a one way ticket to Hell. But before death, the corrupted, broken, deranged man he'd become would kill the innocent and the guilty alike and Sam would be gone, unable to stop him.

"Hello, boys."

For once in his life, the voice was a relief.

Crowley grabbed Dean's arm at the Mark, held it steady as the killer inside him took the knife and stabbed the demon.

It was a normal knife, and Crowley just allowed Dean to stab him, over and over.

"Dean." Crowley said firmly, "You don't wanna kill your brother."

Dean said nothing, no trace of emotional understanding in his eyes.

"Get out of my way."

"Dean, please-"

"Shut up, Sam."

He was shaking so badly it was a wonder how he continued to grip the knife. He started closing the gap between himself and Sam but Crowley continued to separate them.

"I swear, Crowley, if you don't-"

Crowley wrapped his fingers around Dean's forearm, the Mark burning him viciously, but he ignored that.

He began to recite what sounded like a spell in Latin. Dean closed his eyes as whatever it was took effect but it wasn't enough, the power coursing through him fought against the attack like white blood cells attacking a virus.

Sam watched the visible shift in Dean's now open eyes. They stare daggers into him and then soften. Dean struggled against Crowley's strength and he was sapped of the Mark's power. At least for now.

"Sammy?" Sam's brother said.

"Stop it." Cain's descendant said.

"Oh _god_." Sam's brother said.

"Let me have him!" Cain's descendant said.

"Dean!" Sam said, reaching out towards him though Crowley used his free arm to hold him back, "I know you're in there, I can see it, you can fight this."

Cain's descendant laughed a manic laugh of hysteria and Sam's brother bit it back with a pained kind of gasp.

"I'm a fucking monster." Dean said, and Sam couldn't be sure which side of him had said it.

Crowley continued the incantation and Dean fell, power drained from him. He struggled to be upright and managed to rasp out before succumbing to the dark that tempted him,

"You were right," he looked at Sam, Crowley standing off to the side, "Something _is_ broken here. Me."

And then he let the darkness take him and sank into unconsciousness, leaving Sam to wonder what he'd really meant when he said something was broken between them. Surely he hadn't meant Dean. Surely there was blame on both sides. Surely he hadn't told his best friend and older brother that the reason they couldn't be brothers was because the older was so damaged that relationships just weren't possible with him. With someone who tortured and killed and lied and did whatever he thought in the moment was right which could range from anything from saving your hide or taking a life. Or both.

Surely he hadn't meant that Dean was so afraid of being alone because he _was_ alone.


	10. Chapter 10

_* I hope it's not too obvious that I'm not sure how to end this, I hope you enjoy it regardless though. __**Read and review.**_

* * *

Sam sat by Dean's bed, wrought with anxiety that he had rarely experienced before. While he still thought it was time for him to let it go, he was starting to see Dean's side to the demon blood. And Lucifer. And losing his soul. And even the end of the trials.

On the one hand, he knew Dean wasn't himself. He had done this to himself but he wasn't in control anymore. But it's hard to not be hurt when your older brother points out all your flaws and then tries to kill you.

But then on the other hand he was also fearing for Dean's life. He was proving to not only be dangerous to others but to himself. He was getting so desperate for a peace of mind, Sam feared what he might do to get it. While also fearing who he'd take down with him.

Crowley wandered into the room and Sam couldn't find it in himself to question the demon's motives anymore. Crowley checked the lock on Dean's handcuffs habitually and then returned to Sam.

"It's not really him. You know that, right?" Crowley said.

"Part of it is."

"The kill-crazy, codependent bastard you see? The one who'd sell his soul or let an angel in you before he let you die? _That's_ your brother." Crowley's voice was direct and to the point but there was a softness to it, "The ruthless psycho that tried to kill you so he wouldn't have to keep saving you? That's Cain."

Sam looked passed Crowley at Dean.

"You think those cuffs are gonna hold him?"

"For now. However, as my last plan to just let him blow off homicidal steam until we can nab Abaddon proved horribly ineffective, I think we oughta detox Pat Bateman over there until such a time as we can get the demon whore."

Sam looked at Dean, remembered the hours he'd spent in the panic room. Remembered the agony he'd had to endure. The agony Dean had made him endure.

"Alright." Sam said, standing up, "What do we do?"

* * *

Sam had moved a cot down into one of the dungeons, and tried to ignore the 'precautionary' devil's trap Crowley insisted he paint on the floor. Sam felt a horrific feeling of betrayal in himself as he unlocked the cuffs and left the room to lock the heavy iron door.

Just as he closed it, Dean woke up.

"Sam?" He croaked.

Sam tried to pretend he hadn't heard it but then Dean tried to open the door.

"Sammy. I'm not gonna-"

"Dean-"

"You didn't let me finish my sentence..." Dean mumbled, "I said, I'm not gonna hurt you."

In a less emotionally stressful situation, Sam might've laughed at the obvious Shining reference. But given its actual context in the movie, it was more than a little disconcerting.

_"I said, I'm not gonna hurt you. I'm just gonna bash your brains in. Bash them right the fuck in!"_

But for whatever reason, maybe because he knew he'd done the same to Sam or because he'd realized he needed this, Dean just said,

"I'm sorry."

And then was quiet. For now.

But Sam knew that couldn't last.

* * *

_I deserve this. I need this. I did the same to Sam when he needed it. I'm fine. I'm okay._

These thoughts played on repeat through Dean's head as he tried to drown out the painfully loud sound of his rapid heartbeat. And try to overpower the thoughts that we're clawing to the forefront of his mind no matter how he pushed them back.

_He thought he was stronger than you. Smarter than you. Better than you. And for so long he'd been right but you have the upper hand now._

"Stop it. No."

_I deserve this. I need this. I'm okay. I'm okay._

He climbed off the cot and started to pace, trying to keep his thoughts from the delusional direction they were taking to no avail.

A slightly more frightening version of himself manifested from his overheating mind stood before him. It's mark was glowing with black veins spreading like a jagged web up his arm, up his neck, just beginning to creep up to the side of his face.

"He always thought he was better than you, that he didn't need you."

"Piss off." Dean said, holding his head as pain pounded against his skull.

"You're weak. Pathetic." Hallucination Dean sneered, the veins circling his eye.

"Hey, you too then, buddy. Now get out of my head." Dean said, turning his back on the thing but it appeared before him again.

"Desperate. Dependent." It continued, ignoring him, "So worthless and self-loathing that your father and brother's condescending voices are all you ever hear telling you you aren't good enough-"

"Shut up-"

"Because your own embarrassingly low opinion of yourself is worth nothing to you next to your brother's and your dead father's. What'd you care what you think of yourself if they don't love you?"

"Sam-"

"You don't even deny your father didn't love you! You need me!" The veins spidered across his forehead, encompassing the other eye, "I make you strong, and their opinions don't matter any more. It's just you, me, and the Blade."

Dean turned away, gripping his sweat soaked hair, "Wake up... Wake up..."

The veined Dean closed his eyes, the veins suddenly glowed as bright as the mark and when he opened his eyes they shined black.

He smiled and then had Dean against the wall by his throat.

"You're awake, Dean! Alert! Embrace this! Embrace me! The killer the _father_ of killing knew you could be."

Dean struggled, wondering if there was any possibility this hallucination was real or whether he was just having a hard time breathing.

"I'm nothing like Cain." Dean gasped.

Demon Dean dropped him, let him slide down to the floor.

* * *

Tortured and sick as the Mark sizzled on his arm, Dean was sweating badly and he could feel his own thready pulse coursing through him.

He couldn't sleep. He could never sleep. He laid down on the cool floor, his sweat soaked t-shirt retaining some of the cold. He stared up at the dim light that was still managing to stab through his brain.

He stood up, and climbed up on the cot, getting a little more height he pulled the panel off the light and through it on the floor. He grabbed the bright hot light bulb rod in his fist and ripped it out. It broke in his hand but he didn't really feel it.

He climbed down and sat on the floor. He looked at his bloody palm and smiled.

* * *

Sam walked back and forth from the table to the doorway in an agitated sort of way, glancing over at Crowley every other step who was just paging through the first edition of Busty Asian Beauties.

"How long is this gonna take?" Sam asked irritably.

"Who knows?" Crowley said, not looking up from the magazine, "I'd guess a day or two more at most based on my experience of about... Nothing."

Sam rolled his eyes but Crowley continued, "I've got no clue, Sam, I've never detoxed a kill-crazy, Mark of Cain muppet before."

Suddenly the sound of soft laughter carried up the corridor. Sam and Crowley both turned their heads toward the source, though they knew it was Dean.

The two returned to the hallway outside the dungeon where Sam peered in the door through the tiny grate just at eye level.

"Oh god." Sam mumbled, pushing the door open without hesitation.

The glass from the broken ceiling light was littered all over the floor. In the center of the mess was Dean, scribbling words on the floor and walls with his own blood.

Sam walked in slowly, not wanting to startle Dean and as he entered, he began to read some of the writing:

_Kill Abaddon._

This was repeated several times. Then:

"_You'll get used to the feelings. Even welcome them_."

And then:

_Bad blood_

_"I felt connected to you right from the beginning."_

_First Blade_

And scrawled in huge script, the most blood used out of all other writing:

"_No, Dean. I wouldn't."_


	11. Chapter 11

_*I apologize for continuing to make you wait for chapters, I'm just trying to tie this up some how but we'll see how long that takes... Anyway, enjoy. **Read and review.**_**  
**

* * *

Sam felt a cold grip in his chest when he read the words. He could hear his own voice saying it from weeks ago but he knew the voice was even clearer in Dean's mind, however feverish and deranged it might currently be.

Sam took a few cautious steps closer to Dean, hoping to assess the damage he'd done to himself without provoking any further rage. Each step closer was accompanied by a strong desire to retreat, he didn't want to face this. He didn't want to face the fact that his words now bared consequence when coupled with the twisted mind of his kill-crazy brother.

"Dean?" he forced himself to say.

Dean raised his head and stared at Sam. His eyes were having trouble focusing but once they did they were as dead as they'd been when he'd last seen them open. Despite this, he gave Sam a weak, tired smile and said,

"Hey."

Sam slowly knelt down beside him, seeing Crowley put out a warning hand out of the corner of his eye.

"How're you doing?" Sam asked nervously but with a conviction that he hoped would sound convincingly in control.

"I fucked the light up a little." Dean said tonelessly, gesturing vaguely toward the ceiling.

Sam glanced up and then back at Dean, "I can see that. Here, let me look at your hand a second."

Dean didn't offer his hand but he didn't reject it when Sam picked it up himself.

If he wanted to kill Sam now, it seemed he just didn't have the energy to.

Sam examined the damage and then looked up at Dean again.

"This is pretty deep, I should probably stitch it."

That seemed to register and Dean withdrew his hand quickly, looking anywhere but at Sam.

"No, no, you, uh... It's fine, just go." He looked around at his writing with a coherency that hadn't been there before, "I promise I'll stop finger painting, just go, I'll be fine."

Sam stared at Dean, perplexed and also curious as to his state of mind. Incoherent. Coherent. Homicidal. Reasonable. Insomniac. Narcoleptic. He seemed to be flying from each end of the spectrum with such remarkable frequency that Sam wondered if he'd ever reach equilibrium.

"Go." Dean said with a hint of urgency this time.

So, he's leaning towards homicidal again, Sam thought.

Despite not knowing what was going to happen to Dean the longer he stayed here, Sam knew it was best he leave him to whatever it was.

"I'll just clean and wrap your hand and I'll go, alright?"

Dean nodded but looked uncertain. Like he was fighting something back but he wasn't sure how long he could.

Sure enough, by the time Sam returned, Dean had retreated into himself and all that remained on the surface were the dead eyes that blacked out the darkness hiding behind them.

"Dean?"

"Careful," Sam jumped turning to see Crowley standing in the doorway, "The trap is broken."

He walked in and touched the scratched up paint in the Devil's Trap with the toe of his shoe.

Sam didn't say anything. He bit back the desire to repaint the circle because he didn't really need it. Did he?

He approached with caution but Dean was entirely unresponsive. Behind him, Sam heard Crowley get the can of spray paint from outside the door, but he ignored it.

"Dean."

Crowley sprayed down a red strip of paint, repairing the trap, and he backed away towards the door.

Sam stepped over the older lines of the trap, touching Dean's shoulder gently, hoping the contact might shake him.

And it did.

Dean was on Sam in a second, pinning him to the ground he was choking him. Sam tried to repeat his brother's name, scream, anything to reach the deeply stuffed away person that was really Dean. But he couldn't make a sound.

Crowley had rushed back in and tried to reach in and separate the brothers but the trap restricted his reach.

"No, no..." Dean hissed through gritted teeth, trying to pry his hands off Sam's neck.

Sam joined in the struggle, trying to remove Dean's abnormally strong grip from his throat.

Finally, Dean let go. While shaking his head to avoid blacking out, Sam crawled backwards away from Dean.

"I'm sorry." Dean croaked, "I'm sorry, I'm sorry..."

He picked himself up and reached out to help Sam and stopped abruptly. He reached out, stopped abruptly. His eyes fell on the Devil's Trap that ended just where his arm length was restricted to.

Fear and panic flooded his system and he looked to his younger brother who was using the wall to stand himself up.

"What... What does that mean? Sam-"

Sam turned away from him, tears shining in his eyes, he left the dungeon, followed by Crowley.

"Sam?" Dean called after him, "Sammy?!"

He felt destroyed. Ashamed. Broken. And he deserved it. And Sam was smart to leave and Dean hoped for his brother's sake that he'd get as far away from Dean as possible.

Despite how desperately the now conscious and aware Dean needed him.

* * *

Dean laid on his back, staring up at the ceiling but not seeing it. The only thing he could focus on was the voice of a dream from years ago.

_"You can't escape me, Dean! You're gonna die! And this? This is what you're going to become!"_

He'd been so afraid, before going to Hell that he'd become a demon down there. But he didn't. He'd become something much worse. An unrestricted version of himself. He wasn't corrupted he was freed.

And it had felt good.


	12. Chapter 12

* _I'm really excited for the next three episodes to see how the MOC thing develops but until then, here's chapter 12. __**Read and review.**_

* * *

Sam stormed out into the kitchen, trying to stop the tears in his eyes from falling because the last thing he needed was to break down. In front of Crowley no less.

"Sam-"

"This isn't getting any better, Crowley!" Sam shouted, turning on Crowley.

"What do you want from me?!" Crowley said, "If you could detox from demon blood I assumed the same principals would apply! No one ever wrote a manual for this! There's no demonically addicted, codependent, jawlines with daddy issues tablet, I'm just testing out a theory."

Sam exhaled heavily through his nose, turning away in an attempt to mask the fear and the hurt he felt inside watching his brother become what he was becoming. And feel that hatred that was either being forced into Dean or worse, forced out.

"Why're you trying to help anyway?" Sam demanded, turning around, "What'll you get out of this if Dean's okay?"

Crowley rolled his eyes, "Being besties isn't enough for you?"

Sam said nothing, just stared daggers into Crowley, waiting for an answer.

"Alright, fine. Your brother gets this under control, he can control his monster and when he kills again the power of that relapse will destroy Abaddon without so much as a scuffle. And once she's dead, Dean can give me the Mark, and the two of you can jump back in the Winchester mobile and bicker and hunt monsters and everything will be like it used to be."

Sam almost laughed at that.

"You think we'd let you have the Mark? There's no way we'd let you just walk away with that kind of power!"

"Calm down, moose, it'll be a fair trade. Transferring the Mark is the only way to get rid of it. And after being reinstated as the king of Hell, I might need an edge in order to keep our worlds relatively apart. No more wars, no more apocalypse, just demons making deals and humans living out their sad existences like it was before the winged bastards got involved."

* * *

Slipping into an uneasy kind of half sleep, Dean's dreams were interlacing with memories and snippets of Pink Floyd.

_"Ever since you killed Magnus you've been acting... Kind of... Obsessed."_

_Hello, is there anybody in there...?_

_"Well, maybe because I want an end to all this. Maybe because if we find Abaddon, then Crowley ponies up the First Blade, and we kill her and him both. So, what you call 'obsessed', I call doing my job."_

_Just nod if you can hear me..._

_"Okay... I get it, Dean, I'm just checking in."_

_Is there anyone home?_

_"I'm fine."_

Dean felt his skin crawling, feeling every drop of sweat bead up in his pores and form a thin film over his whole body.

_Come on, now, I hear you're feeling down..._

He needed the blade. Desperately. The Mark was eating him alive in its desperation for its companion and Dean was helpless to fight it.

Every time a wave of homicidal rage came over him, that part of himself he'd always tried to bury, the 'worthy' part of himself that just barely skimmed the surface when hunting, would enjoy it.

Part of him loved the graphic, vivid homicidal ideation and the Mark only made it worse. But it had always existed.

_I can ease your pain..._

The Mark burned on his forearm. And part of him wanted to embrace it. Just break out somehow and slaughter anyone an everyone in his path until he bloodlust was satisfied. But the other part of him wanted to hack the thing off his arm. Unfortunately Sam had come by, not saying a word, and collected up all the broken glass and left with it, so there was nothing to scrape it off with.

_Get you on your feet again._

* * *

Dean scratched at the mark. Images of murder and torture flicked through his head and he only scratched harder. Nails grinding against skin he was beginning to make minor abrasions in his own skin but he didn't stop.

_What if I kill some innocent person? I almost did with that Shifter. I would've if Sam hadn't stopped me._

Blood gushed from the scratches and they were only getting deeper.

_What if this detox kills me... Never mind. I hope it does._

Breaking through muscle now. Still the mark burned. His nails were stuffed with skin and blood.

_What if I kill Sam?_

Scratching. Digging.

"_Abel wasn't taking to God, he was talking Lucifer. Lucifer was gonna make my brother into his pet. I couldn't bear to watch him be corrupted so I offered a deal."_

He might've hit bone.

"_Abel's soul in Heaven for my soul in Hell._"

Dean looked down. He arm was gaping open, flesh as muscle peeled apart, blood everywhere and remnants of all of it under his nails.

"_Lucifer agreed. As long as I was the one who sent Abel to Heaven_."

But even amongst the muscle and bone, the Mark was burned hard and black against it.

"_So I killed him._"

Dean jolted awake, his heart was racing and he was having difficulty breathing. He sat up on the cot, pushing his sweaty hair off his forehead, and looked down at his arm. It was still whole, no visible scratches. Just the mark.

Imprinted to his very bones.


	13. Chapter 13

_* This is where this fic will branch out into actually fictional as episodes from "King of the Damned" onward take the MOC in a different direction than this story. Sorry for the wait, but holy shit, did you guys see "Stairway to Heaven"? Anyway... here's the next chapter. A few more after this I think to wrap it up soon-ish._

* * *

Sam had been sitting at the conference table for two hours listening to the broken screams of his psychotic, overheating brother. Crowley was having a look in the liquor cabinet when Sam stood up suddenly.

"Can you take it from him now?"

"What?"

"Take it, take the Mark, you can have it, just, can you do it?"

Crowley stood up and faced Sam.

"Are you off your bloody rocker? Last time we saw him he nearly broke your neck trying to choke you, and you want me to just walk into the trap and be stuck with the person who explicitly told me I was next on his list after Abaddon? No, I'll wait until he's clean, thanks."

Sam turned towards the strangled yells of his older brother.

"He's dying, Crowley, or something worse, just, please-"

The screaming was crossing over into hysterical laughing.

Crowley hesitated for a moment and then started heading towards the dungeon. Maybe it was because he actually cared. Maybe it was because Sam was practically begging. Or maybe it was because he didn't trust the human monster who couldn't possibly handle this amount of power.

The demon stepped into the dungeon and found, to his considerable surprise, that Dean was sitting quietly within the confines of the devil's trap. He was closed in on himself, arms folded over his chest, propped up by the corner between the cot and the wall. He had his head down, eyes closed. Though barely audible, both Crowley and Sam caught it upon their entry, Dean was humming.

"What is that?" Crowley hissed to Sam.

Sam answered with little hesitation, his voice on the verge of breaking he said, "It's Metallica."

_"Are you humming Metallica?"_

_"It calms me down."_

In that instance he was just nervous about air travel, now he was possessed by a demonic mark that made him so homicidal he had to worry that Sam might just become a fragile meat suit to him to dismember.

Sam took a deep breath and approached his brother, recognizing the song as 'Some Kind of Monster' and trying not to read too much into that.

"Dean."

Dean looked up, still humming, and Sam made an involuntary jump back. One of Dean's eyes was empty and black, the other was lost, scared green.

"You have it." Dean said softly as the humming stopped.

"What?"

"The Blade."

Dean was pointing toward Crowley who was hanging back a little.

Sam turned back and saw Crowley heading towards the door. Sam crossed the room and stopped him at the threshold.

"What the hell, Crowley?! You've had it on you this whole time?"

"What'd you expect me to do with it? Put it in a safe deposit box until we nab Abaddon?"

"It should be as far away from him as possible." Sam whispered.

"Right, okay, I'll stick it somewhere for safekeeping, alright? I just-"

Crowley's coat flapped open and the Blade flew out, directly into Dean's outstretched hand.

Sam and Crowley turned to watch in horror as the mark glowed white hot, and any trace of reason or feeling was wiped from Dean's eyes.

He stared at the trap, and the floor cracked, breaking the red, painted lines. He stepped out over them and started towards Sam. Crowley stepped between them.

"Hey, hey, calm down, squirrel, we'll-"

Dean grabbed Crowley's head and twisted it. His neck snapped with a loud crack and Sam jumped back.

Dean turned to Sam, Blade wielded.

"Dean. Dean, stop- you can stop-"

"Who says I want to?!" He growled back, advancing on Sam.

Sam hesitated a moment, trying to piece together anything that might calm Dean, but nothing left to be said would reach him now. Sam took a few steps back, turned, and bolted.

Running down the hallway he heard Dean not far behind him.

"Sam!" Dean yelled.

Sam hooked around the corner and into a spare bedroom. He locked the door and leaned heavily against it as Dean caught up outside.

_"All you've ever done is run away!"_

Sam shook his head. The voice of that memory had no context here. Sam wasn't giving up he was protecting his own life.

_Giving up on your brother. Blocking him out._

"SAMMY!"

No. Dean was possessed by power and trying to kill him. All he could do is run-

Dean was heaving his body against the other side of the door now. Sam had to get out of here-

_"It's okay, Sammy. It's okay. I'm not gonna leave you."_

Sam froze.

When he'd been possessed by Lucifer he'd been terrified. Stuffed inside himself, helpless to control anything he said or did. And while he didn't want to hurt Dean, without him he wouldn't have taken control. He wouldn't have been brave enough without his brother riding it out with him.

_"It's okay, Dean. It's gonna be okay... I got him."_

Sam grabbed the shaking doorknob and bellowed through the wood,

"You can fight this, Dean! You don't have to kill me!"

"Come out, come out, Sammy!"

Sam took a breath, prepared himself to leap back, and opened the door. Dean had the Blade raised above his head, twisted bloodlust raging in his green eye while the black on showed nothing but the emptiness that was taking over. Sam leapt out of Dean's path, slipping out the door, he faced him, slowly backing away. But not leaving. Never leaving.

"Dean, I know, you feel powerful," he dodged Dean as he tried to punch him, "And you feel like the Blade is the only thing that'll make you feel strong-"

"Strong?! I've been _rotting! _Dead inside for _months_, hell, _years_, first time I held this Blade, I felt more alive than I ever have, and I'm sorry, Sam, but I am not letting this go." Dean said, his voice dripping with brutality but he was coherent.

He knew what he was saying.

"Dean, none of it's real! You're not happy, you're strung out, that's all it's doing for you, man!"

Dean gave a gruff kind of yell as he lunged at him, mark burning bright orange on his arm, Blade inches from Sam's head.

Sam ducked, backing toward another doorway, he opened it and backed inside, letting Dean follow him. Another trap was painted there, on the ceiling this time. Dean stuck, and looked at Sam, smirking with a dark laugh.

"Really? We tried this already, Sam, and I busted up the fuckin' floor."

Sam reached into his back pocket and pulled out the demon cuffs, snapping it swiftly around Dean's wrist and then on a pipe on the wall. Dean roared with a savage, monstrous snarl. He barely looked human. But it wasn't quite demonic. Even demons would fear this.


End file.
